The piping stress analysis shall include the
following loading effects as applicable.

3.1. Piping Stress Analysis - Weight Effects

The weight load shall include the pipe weight,
weight of content, insulation weight and weight of fittings and any inline
equipment. For piping systems, which are tested hydraulically and have content
with specific gravity less than 1.0, a hydro-test run shall be performed
assuming a specific gravity of 1.0 to establish the structural design loads.

3.2.Piping Stress Analysis - Thermal Effects

Temperature to be used in the piping flexibility
analysis shall be the maximum differential temperature between any of the
following applicable conditions.

3.2.1. Piping Stress Analysis - Installation Temperature

1) Maximum dry bulb temperature of 48°C shall be
taken as the installation temperature for cold insulated piping service.

2) Minimum dry bulb
temperature of 5°C shall be taken as the installation temperature for bare/hot
insulated piping service.

3.2.2. Piping Stress Analysis - Calculation Temperature

1) Operating temperature as stipulated in the line list.

2) In addition, the following temperature condition shall be considered in
the calculation when lines are specified in the line index.

Start-up / shutdown
temperature

Steam out temperature:
Normal steam out temperature should not exceed 120°C for saturated steam. This
steam out temperature shall be considered only for flexibility purposes of
hydrocarbon serviced lines.

Decoking temperature

Regeneration
temperature

3) For piping which normally have no flow
(such as drains, start-up lines, etc.) the flow calculation temperature shall
be determined as follows.

For insulated piping,
75% of operating temperature shall be taken.

For un-insulated
piping, 25% of operating temperature shall be taken.

For section between
stand-by equipment and cut-off valve, installation temperature shall be taken.

For piping which have
warming-up by-pass, operating temperature shall be taken for all section.

3.3. Piping Stress Analysis - Pressure Effect

Maximum operating pressure and minimum
vacuum pressure shall be taken as the calculation pressure as per ASME B31.3,
unless otherwise specified.

3.4. Piping Stress Analysis - Friction Effects

3.4.1 Friction effects shall be considered in the design
of anchor on horizontally long run piping system with OD larger than 8 inch.

3.4.2 Following friction factor shall be used for
computing the frictional resistance.

Surface

Friction Factor

Steel to Steel

0.3

Steel to Teflon

0.1

Teflon to Teflon

0.06

Steel to Concrete

0.5

3.5. Piping Stress Analysis - Wind and Earthquake Effects

3.5.1. Wind and earthquake effects shall be checked in formal computer analysis, if experienced stress engineers decide it necessary. Wind loading shall be considered for sizes 24NB and over, for heights more than 10 m above grade where not shielded. For earthquake loading the equivalent static force analysis method shall be applied. The wind load and Earthquake as acting separately in two lateral condition 90º apart. 2.

4.1. Piping to purged vessels that cannot be disconnected during purging shall be designed with sufficient flexibility to accommodate the thermal displacement of the vessel.

4.2. The use of cold spring in piping, which connects to rotating equipment, is prohibited.

4.3. If temperature, resulting in short term loading as those stated in Para. 3.2.2.2) is specified in the line list, thermal effect by this temperature shall also be considered in the analysis. However, the reaction loads at equipment shall not be taken from this alternate analysis case.

4.4. Flexibility

1) The required flexibility of the piping shall be achieved by a suitable layout configuration without the need for expansion joints, first. Expansion joints shall be used only where bends, offsets or expansion loops are not deemed feasible. In this case, the stiffness of expansion joint shall be considered in any flexibility analysis. And, the destabilizing effects of unbalanced pressure thrusts shall be accounted for in the piping design.

2) Expansion joints shall be used only with adequate guides and anchors and when the fluid plugging properties cannot make the expansion joint ineffective.

3) Bellows
type expansion joints shall be avoided in services that cooking can occur. If a
suitable piping configuration can not be designed to eliminate the joint,
connections shall be provided to enable flushing of the area between bellows
and liner to be carried out in a non-coking medium.

4) Torsional rotation of the bellows
shall be avoided. This twisting generally produces extremely high shear
stresses in the bellows so where torsional rotation cannot be avoided; special
hardware shall be used to limit the amount of torsional shear stress in the
bellows.

5) The maximum, minimum and
installation temperatures shall be accurately stated in data sheet to be
prepared by the designer. Where the ambient temperature can vary significantly
during pipeline construction, pre-positioning of the Expansion Joint at installation
may be required.

6) The Expansion joint manufacture shall be
advised if the Expansion joint will be insulated and the manner by which the
Expansion joint will be insulated in order to properly design the component
parts.

7) The movements to be absorbed by
the expansion joint shall include not only piping elongation or contraction,
but also movement of attached vessels, anchors, etc. and the possibility of
misalignment during installation. Unless included in the design requirements,
misalignment of the Expansion joint shall be avoided.

8) Where movements are cyclic, the
number of cycles expected shall be specified. As in the case of pressure, the
movement specified shall be realistic. An excessive safety factor can result in
an Expansion joint, which is unnecessarily flexible; thus its stability under
pressure is unnecessarily reduced.

9) If the flowing medium can pack or
solidify, provisions shall be made to prevent entrapment or solidification of
the material in the convolutions, which could result in damage to the Expansion
joint or pipe line.

10) The predicted amplitude and
frequency of external mechanical vibrations to be imposed on the bellows, such
as caused by reciprocating or pulsating machinery, shall be specified. A
resonant condition in the bellows will result in a grossly reduced fatigue life
and shall be avoided.

4.5. The flexibility analysis shall be in accordance with
ASME B31.3 and shall be based upon the total displacement strain imposed upon
piping system including the effects of equipment settlement or anchor movement,
if applicable.

4.6.. The computed stress
range shall be less than allowable stress range as defined in ASME B31.3 unless
otherwise specified.

4.7. Thermal
movements shall be limited to 300mm between anchors and to 100mm at pipe bends
or turns. However, greater movements will be considered if the availability of
space and the capacity of the anchorage to accept the incremental loads are
confirmed.

4.8. Start-up, shut-down and steam-out where applicable and upset
conditions including short-term excursions to higher temperature or pressure as
well as normal operating conditions, shall be considered in flexibility
analysis. This is particularly pertinent to loads applied to connecting
equipment. The effect of vibration from machinery on connecting piping shall
also be assessed.

4.9. Flare system piping shall be designed to take care of
expansion, movement or vibration caused by the most severe operating or
emergency conditions. Pipe shoes or saddles shall be furnished on the main
flare header at all supports.

4.10. Cold spring shall be used as much as practical to reduce
forces on equipment nozzles and to prevent interference from expanding lines.

4.11. The use of cold spring for piping systems,
which connected to rotating equipment, is prohibited.

4.12. The
combinations of the loads shall conform to the applicable piping code.

5.1.Each piping system shall be classified as grade “A”, “B”
and “C” according to the severity of its design condition and need for
special design. Each grade requires the following methods for stress analysis.

Grade “A”: Judgment
based on the experience of stress engineer.

Grade “B”: The
simplified method according to Para.319.4 of ASME B31.3.

Grade “C”: Formal
computer analysis.

5.2. For
the following 3” and larger lines, formal computer stress analysis method is
required:

Process, regeneration and decoking lines to and from Fired Heaters and
Steam Generators.

Process lines to and from Blowers.

Steam lines to and from Turbines.

Suction and discharge line of Pumps.

Suction and discharge line of Compressors.

5.3. The judgment of grade
for all piping except that connected to rotating equipment shall be in
accordance with the criteria shown on fig.1.

5.4. The judgment of grade
for all piping connected to rotating equipment including air fin cooler and
fired heater shall be in accordance with the criteria shown on fig.2.

6.0. External Load Limits on Equipment

6.1.Rotating Equipment

The allowable nozzle loads for rotating equipments shall
be limited to those specified in their governing Engineering specifications and standards to which the equipment is
designed, unless otherwise specified by applicable vendors.

For
ANSI and ISO pumps, allowable nozzle loads shall be those as other stated in
table 2 of API 610 unless otherwise specified by vendors.

6.2. Air Fin-Cooled Exchangers

The
allowable nozzle loads for air fin cooled exchanger shall be limited to those
specified in Engineering specifications
and vendor recommendation and API 661. Piping to air fin cooled exchanger
shall be designed to take into account clearances between the frame and the
header box of each bundle. And, thrust blocks between tube bundles shall be
used whenever possible to minimize friction loads at piping takeoffs and
anchors, and to meet allowable loads at the nozzles.

6.3. Exchangers (Shell and Tube)

For piping connected to heat exchangers with
T<400°C or P<35 kg/cm2g, the pipe bending stress due to thermal expansion
at the exchanger nozzle shall be limited to 700 kg/cm2 using a rigid nozzle
analysis. If above criteria is exceeded, localized stress at the
nozzle-to-shell be calculated by WRC 107 and WRC 297, and these computed stress
value shall be limited in accordance with ASME SECTION VIII.

For piping connected to
heat exchangers with T>400°C or P>35 kg/cm2g, the piping
imposed loads shall be transmitted to the vendor for his approval.

6.4. Pressure Vessels and Columns

For piping connected to pressure vessels and
columns with T<400°C or P<35 kg/cm2g, the pipe bending stress due to
thermal expansion at the pressure vessels and columns nozzle shall be limited
to 430 kg/cm2 using a rigid nozzle analysis.

If above criteria is exceeded, WRC 107 and WRC 297
shall be used for calculate localized stress at the nozzle-to-shell, and these
computed stress value shall be limited in accordance with ASME SECTION VIII.

For piping connected to
pressure vessels and columns with T>400°C or P>35 kg/cm2g,
the piping imposed loads shall be transmitted to the vendor for his approval.

6.5. Fired Heaters and Steam Generators

The allowable nozzle loads and moments for fired heater shall be
limited to those specified in relevant
Engineering specification or API 560 or values that are acceptable to
heater vendor.

Displacement
of tubes shall be approved by the
heater vendor and the effect of expansion and/or displacement of the tubes shall be reflected in the stress
analysis of piping system.

Any heater
designed with a floating coil (all spring or counter weight mounted) shall be
provided with fail-safe limit stops in all directions.

Computer
analysis of piping systems connected to floating heater coils shall include the
heater coil or an approximate model of the coil as part of systems and the
effects of internal guides and restraints. Where heater coils are floating, the
support of the connecting piping system shall be completely and independently
balanced so that no dead loads imposed on coil.

6.6. Packaged Equipment

External load limits are to follow the vendor
recommendations.

7.0. Piping Restraints

7.1. Pipe supports shall be
spaced so as not to cause excessive deflection at any point along the
unsupported section of the pipe. As a
general guide for piping located in process area, the maximum mid span
deflection shall not be allowed to exceed 12 mm and for piping in pipe way, the
mid span deflection between straight run of piping shall not be allowed to
exceed 12 mm.

7.3. Piping subjected to two-phase flow and connected to reciprocating
compressor shall be supported as rigidly as possible while maintaining acceptability
of pipe stresses and equipment nozzle loads.

7.4. For
nonmetallic piping, vendor’s recommendation for flexibility analysis, support spacing and support type shall be
utilized.

8.0. Miscellaneous

8.1.Reports

Final calculation of the grade “C” and the
grade “B” which are analyzed by formal computer analysis will be
submitted to owner for record and site modification of piping. The piping
systems which are classified as grade “B” shall be analyzed by formal
computer analysis if experienced stress engineers decide it necessary to prove
that the systems meet the allowance of this specification. The reports shall
comprise of the following:

Basic data and calculated conditions

Layout isometric and support type and
location

Load cases and calculated member stresses

Forces, moments and displacement reports

Spring hanger and expansion joint design
parameters

8.2. Units

Metric units (kg, mm, kg-m, kg/cm2) shall be used as
a unit of control for analysis.

8.3. Softwares

CAESAR II Ver 4.2 (produced by COADE Inc.) will be
used for formal computer analysis.